1. Field of the Invention
The present invention relates generally to telecommunications and, more particularly, to managing hybrid automatic repeat request (“H-ARQ”) transmissions in a wireless communication system.
2. Discussion of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
One of the paramount challenges facing modern wireless telephone systems is the rapid growth of consumer demand for data services such as Internet access, text messaging, and e-mail. In fact, consumers are demanding greater access to data-related services than ever before, and this trend is not likely to change. For example, in the coming years, consumers will likely expect their wireless telephones to provide many, if not all, of the communication features currently provided by computers (e.g., video conferencing, picture mail, etc.).
Unfortunately, building or upgrading the telecommunication infrastructure to support growing consumer demand is relatively expensive. As such, much research has been invested into determining better and more efficient methods for transmitting information over existing infrastructure. One technique, known as Hybrid Automatic Repeat Request (“Hybrid ARQ”) is employed in many wireless systems (for example, Evolution-Data Optimized (“EVDO”) Evolution-Data and Voice (“EVDV”), and High Speed Downlink Packet Access (“HSDPA”)) to increase data throughput or transmission efficiency.
Typical Hybrid ARQ systems work in the following manner. First, information and/or data is encoded with some amount of redundancy and packetized into encoded packets. The encoded packets are then segmented in multiple sub-packets (four, for example). The encoding, redundancy and segmentation are typically designed in such a way that the transmission of any number of sub-packets could result in successful reception of the entire information. For example, if the encoded packet is split into four sub-packets, the reception of just one, two, or three sub-packets may be enough to successfully decode the entire packet.
To take advantage of Hybrid ARQ operation, a receiver provides “fast” feedback after every sub-packet to indicate the status of the packet reception. More specifically, if the packet cannot be decoded after processing a particular sub-packet, the receiver may send an explicit or implicit non-acknowledgement (“NAK”) to the transmitter. In response to NAK, a conventional transmitter will continue sending additional sub-packets until all of the sub-packets are transmitted or an acknowledgement (“ACK”) is received by the transmitter.
As described above, due to the encoding and the redundancy of the above-described sub-packets, all of the data in a particular packet may be transmitted without transmitting all of the sub-packets. As such, once the ACK has been received, the transmitter can stop trying to transmit the remaining sub-packets. This condition is sometimes referred as “early termination.” Early termination may increase system throughput or capacity, because the slots/frames that would have been used by the remaining sub-packets can be used to send different information.
One or more of the embodiments disclosed below may be directed toward improvements to H-ARQ systems.